Testing effects of reproduction on stress and mortality

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DESCRIPTION (provided by applicant): This study will determine the direct effects of the adult ovary on mortality rate in an insect model organism. Reproduction may shorten lifespan in at least two ways: limited nutrients may be allocated to reproductive processes instead of the soma, or reproduction may create direct negative effects on longevity that are independent of nutritional allocation (e.g., release of aging hormones). The effects of calorie restriction on longevity are well studied. The contributions of reproduction that are independent of nutrition are not well understood. In this project, I examine the model of direct effects of reproduction on longevity. This model posits that when germ-line tissue is intact it directly reduces the individual's ability to resist cellular stress or minimize oxidation, thereby increasing age-specific mortality rate independently of nutrition. Grasshoppers are excellent models for this approach to aging because they are large enough for tracking individuals and analyzing multiple tissues, but are shorter-lived (approximately 80 days) and cheaper than mice. Plasticity of reproduction in grasshoppers is well characterized; this proposal extends these studies to plasticity of stress tolerance and age-specific mortality. Aim #1 will test whether ovariectomized females have higher constitutive levels of heat shock protein 70 and superoxide dismutase activity. The model of direct effects on reproduction predicts higher Hsp70 levels and superoxide dismutase activities. Aim #2 will test whether the ovary decreases age-specific mortality rate independently of nutritional allocation to vitellogenesis. The model of direct effects of reproduction on longevity predicts the ovary will decrease mortality rate with decreasing vitellogenesis. Aim #3 will test whether ovarian effects on mortality rate are linked to nutrient allocation. The model of direct effects of reproduction on longevity predicts that ovarian effects do not act through nutritional allocation. Understanding the basic biology of aging is critical to the health care of the nation. Reproduction is known to reduce longevity, but how this can occur independently of nutrition is not clear. Using an insect model, this proposal will examine whether the ovary decreases life-span, without the confounding affects of nutritional distribution. Ovarian control of stress proteins and anti-oxidants will also be tested. Last but not least, this grant will have a profound effect on the research environment in biology at the University of North Florida.